Researcher finds dangerous bacteria in tarballs

But when balls of oil started washing up outside her Dauphin Island Lab after the BP oil spill, the Auburn University professor and her team decided to run a few tests. They particularly wondered whether the tarballs contained any of the lethal bacteria that they track in seafood.

They found that the tarballs — which oil executives and government officials have said are little more than a nuisance — are teeming with bacteria, including Vibrio vulnificus, the leading cause of death from eating bad oysters. In fact, they discovered that the balls had up to 100 times more of that particular bacteria than the water they floated in and 10 times more than the sand they rested on.

“We were surprised,” said Arias, a microbiologist in Auburn’s Department of Fisheries and Allied Aquacultures and the lead writer on a paper the team published on their results online in the journal EcoHealth in November.

Now Arias is seeking grant money to find out more about bacteria in tarballs. Mostly, she wants to know what kind they are and what they’re doing there. Are they benefiting from the degrading oil, or do the blobs just provide a structure? Are any of them helping break down the oil?

“There are a lot of questions,” said Arias, who ran some early tests. For now, they’ll have to wait not just for the funding to roll in, but for the water to warm up, as V. vulnificus is most prevalent during the summer — thus the old warning about avoiding raw oysters from May through August.

Meanwhile, she warns that it’s best to give any tarballs — which show up on Gulf beaches even when there’s not a major spill — a wide berth, even though it’s unlikely most people will get sick from them. Some people do have greater risk from V. vulnificus, especially those with suppressed immune systems and chronic health conditions like liver problems and diabetes, and it can travel through cuts in the skin.

“Tarballs accumulate a lot of bacteria, and they should be treated as you would treat a bad crab or something that is rotten on the beach,” said Arias. “There’s more to it than just being a nuisance.”